There are many different processes and machines which utilize a body that is reciprocated back and forth to perform work. There have always been problems in supporting such a reciprocating body, particularly when the reciprocation is in a horizontal direction. This problem exists in some of the machines used to form can bodies.
A typical method of manufacturing two piece cans consists of making a circular blank and then drawing the blank to form a shallow cup. The cup is fed in position ahead of a punch attached to the ram, and then is formed by the ram through a redraw die and a plurality of ironing dies located in a tool pack housing.
Presses for directing the movement of the ram may be either mechanical or hydraulic. Exemplary of mechanical machines are U.S. Pat. No. 3,702,559 to Hasselback et al. entitled "Can Bodymaking Machine" and 3,696,675 to Maytag entitled "Metal Working Crank and Slide Press Mechanism". The ram in the Hasselback invention slides on guides with an attached cam follower cooperating with cam grooves on a barrel cam. The barrel cam is mounted on a shaft driven by an electric motor. The ram in the Maytag invention is mounted on a carriage with wheels which run on the top and bottom surfaces of hardened way strips. The wheels are adjusted with a predetermined amount of preload to avoid slack in the wheels. The carriage is driven by a crank and connecting rod attached to a parallel motion assembly.
Typically, mechanically driven rams can be driven at high speeds but do not always provide uniform punch speed or travel in a straight line motion, which is critical to continuously producing uniform can walls. The Maytag invention overcomes some of these problems but the movement of a heavy carriage upon which the ram rides inherently requires a significant amount of service time. Wear items such as bearings and cam followers must constantly be replaced. When such items are replaced, the complete ram system must be calibrated and each wheel individually loaded. Regrinding the hardened way strips also contributes to the significant "down time." Reducing "down time" and increasing efficiency is significant in light of the fact that can bodymachines typically run 24 hours per day and produce cans at rates in the range of about 150-230 cans per minute.